Two suicide bombers in Tuesday's attacks at an airport and a metro station in Brussels were brothers who were known to the authorities, according to Belgian federal prosecutor Frederick Van Leeuw.

The two have been named as Khalid and Ibrahim El Bakraoui.

Ibrahim El Bakraoui was identified in a CCTV image from Brussels' Zaventem Airport; he is reportedly the man dressed in black in the middle of three suspected attackers.

The suspects at the airport. Ibrahim El Bakraoui is in the middle of the image; the other two men have not yet been identified. CCTV/Belgium Police Van Leeuw said Ibrahim El Bakraoui was responsible for one of two suicide bombings at the airport. The attack killed at least 10 people and left more than 100 wounded.

A second suspect dressed in black in the CCTV image has not yet been identified but is thought to be responsible for the second bombing at the airport.

The Belgian prosecutor said the other brother, Khalid, detonated his bomb in the Brussels metro while part of the train was still in a station. That explosion killed at least 20 people and injured more than 100.

The RTBF reports that Khalid had rented, under an alias, the house that was raided by the police in the Brussels suburb of Forest last week. He had also reportedly rented an apartment in Charleroi that was raided by the police a few months ago and was used to plan the Paris attacks.

The brothers Khalid and Ibrahim El Bakraoui were identified by a Belgian federal prosecutor as suicide bombers in Tuesday's attacks in Brussels. Belgium Police/Sky News The third suspect in the CCTV image, pictured at the airport wearing a white jacket, has not yet been identified. The Belgian prosecutor said the man had dropped a bag full of explosives in the departures hall and then run away. He is actively sought by the police.

"His bag contained the most explosives,"Van Leeuw said. "Shortly after the arrival of the bomb-defusing team, the bag exploded because of the instability of the explosives. No one was injured."

The man in the white jacket had been identified in news reports as Najim Laachraoui, but the prosecutor's office did not confirm the man been identified. Laachraoui is being sought by the police in connection with the November attacks in Paris.

A newspaper with the headline "Hold Fast!" is held up following a minute silence for victims of Tuesday's bomb attacks in Brussels, Belgium, March 23, 2016. REUTERS/Vincent Kessler

Reuters reported that Laachraoui's DNA was found in houses used by the Paris attackers last year and that Laachraoui traveled to Hungary in September with Salah Abdeslam, the prime suspect in the Paris attacks, who was captured last week in Brussels.

The head of the Coordination Unit for Threat Analysis confirmed on Wednesday that Belgium's terror-threat status would remain at its maximum level.

An antiterror raid was carried out on Wednesday in the Anderlecht region of Brussels, and one person was arrested, the BBC reports. The name of the person detained by police has not been released.

Belgium is in three national days of mourning after Tuesday's attacks, which left at least 31 people dead and about 270 wounded.

Belgian troops at a roadblock near Brussels' Zaventem Airport after Tuesday's bomb attacks in Brussels. REUTERS/Charles Platiau A minute's silence for the victims was held at noon local time (11 a.m. GMT, 7 a.m. ET) to remember those who were killed. Islamic State, the militant group also known as ISIS, Daesh, or ISIL, claimed responsibility for the attack.

The two explosions in the airport happened in quick succession shortly after 8 a.m. Belgian police officials are presuming that the two men wearing black in the photo of the suspected attackers are dead after detonating suicide devices.

The three men in the photo are thought to have come to the airport with bombs in their suitcases. "They put the suitcases in their trolleys," Francis Vermeiren, the mayor of Zaventem, said. "The first two bombs exploded. The third one also put his suitcase on a trolley, but he must have panicked — the bomb did not explode."

According to the Belgian news site VRT, the suspects tried to fit five suitcases in the taxi but had to leave two behind because they did not fit in the car.

The Belgian police have located the taxi driver who drove the three suspects to the airport, Van Leeuw said.

A man at a street memorial after Tuesday's attacks in Brussels. REUTERS/Francois Lenoir He gave the police an address in the Schaerbeek area of Brussels where he picked up the men, according to Van Leeuw, who said authorities found an ISIS flag there along with another explosive device, which was filled with nails and chemicals.

"In that apartment, we found all the elements to make bombs, including 15 kilos of TATP, 150 litres of acetone, hydrogen peroxide, as well as a lot of nails screws and nails," Van Leeuw said.

The police continued operations throughout the night and led numerous raids near the train station in Schaerbeek.

The prosecutor's office confirmed that numerous raids were taking place throughout Brussels and across Belgium. On Wednesday morning the prosecutors had not yet confirmed whether any raids were successful but said many witnesses were still being questioned, the RTBF reports.

A minute of silence was observed Wednesday for victims of Tuesday's bomb attacks in Brussels. Front row, from left: French Prime Minister Manuel Valls, King Philippe of Belgium, EU Commission President Jean-Claude Juncker, Belgian Queen Mathilde and Belgian Prime Minister Charles Michel. REUTERS/Francois Lenoir The attacks came days after Abdeslam, the leading suspect in the Paris attacks, was arrested in Brussels, the de facto capital of the European Union.

Belgian officials have long been aware of the existence of an ISIS-linked terrorist cell in Brussels, believed to be centered in the district of Molenbeek.

Belgium's interior minister, Jan Jambon, has called Molenbeek "the capital of political Islam in continental Europe," and several suspects have been arrested there in connection with the Paris attacks, which killed 130 people.

The Belgian football association announced on Wednesday it was cancelling next Tuesday's international friendly game against Portugal in Brussels over security fears after the attack. "The Red Devils match against Portugal, scheduled for Tuesday evening at the King Baudouin Stadium, will not take place," it said on its website.

Popular from BI Prime

Close iconTwo crossed lines that form an 'X'. It indicates a way to close an interaction, or dismiss a notification.Check mark iconA check mark. It indicates a confirmation of your intended interaction.